Air-cushion vehicles, also known as hovercraft, have been known for quite some time. These vehicles have a hull that has a skirt extending about its perimeter. Motorized fan units ar used to produce a cushion of high pressure air under the vehicle so as to lift it off the ground. The vehicle is then usually driven or propelled over the ground by means of an axial wheel or propeller or more than one propeller.
U.S. Pat. No. 3,662,852 which issued May 16, 1972, to R.V. Taylor describes an air-cushion vehicle wherein the hull has a peripheral bag skirt extending downwardly therefrom. Near the centre of the vehicle is a single engine which provides power to a centrifugal cushion fan for supplying cushion air. Mounted at the rear of the vehicle is an air screw or propeller for supplying thrust to the vehicle. Power is provided to the air screw by means of the same engine acting through a drive shaft, pulleys and one or more drive belts extending about these pulleys.
More recent U.S. Pat. No. 3,860,084 issued Jan. 14, 1975 to Vosper Thornycroft Limited describes an air cushion vehicle which has a propulsion fan or propeller in a fan duct mounted at the rear of a vehicle and inclined at an angle to the horizontal. A long drive shaft extends forwardly from the propeller at the aforementioned angle to the horizontal to a gear box. Power is provided to this gear box through an output shaft connected to a power plant. By means to a suitable gear arrangement, the same power plant is used to drive two sets of centrifugal lift fans mounted forwardly of the gear box.